Quad-channel DRAM

ABSTRACT

A DRAM includes at least four groups of memory cores and at least four memory access channel interfaces that, in a first mode, each respectively are to receive memory access commands, directed to a corresponding one of the groups of memory cores. One-half of the memory access channel interfaces are to, in a second mode, each respectively receive memory access commands, directed to a corresponding two of four of the groups of memory cores. The memory access channel interfaces to have electrical connection conductors that lie on opposing sides of at least one line of reflectional symmetry from a second one-half of the one-half of the at least four memory access channel interfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram illustrating a first mode of a quad-channel DRAM.

FIG. 1B is a block diagram illustrating a second mode of a quad-channel DRAM.

FIG. 1C is a block diagram illustrating example active circuitry when the quad-channel DRAM is in the second mode.

FIG. 2A illustrates a first and second quad-channel DRAMs oppositely mounted to utilize dual-channel mode.

FIG. 2B illustrates, with the substrate removed for clarity, the first and second quad-channel DRAMs oppositely mounted to utilize dual-channel mode.

FIG. 3A illustrates a first example device orientation and active channel connections for a pair of oppositely mounted quad-channel DRAMs.

FIG. 3B illustrates a first example device orientation and active channel connection symmetry for a pair of oppositely mounted quad-channel DRAMs.

FIG. 3C illustrates a first example active to inactive channel connection correspondence for a pair of oppositely mounted quad-channel DRAMs.

FIG. 4A illustrates a second example device orientation and active channel connections for a pair of oppositely mounted quad-channel DRAMs.

FIG. 4B illustrates a second example device orientation and active channel connection symmetry for a pair of oppositely mounted quad-channel DRAMs.

FIG. 4C illustrates a second example active to inactive channel connection correspondence for a pair of oppositely mounted quad-channel DRAMs.

FIG. 5A illustrates a first example device orientation using partial per-channel connections for a pair of oppositely mounted quad-channel DRAMs.

FIG. 5B illustrates a first example active to inactive partial per-channel connection correspondence for a pair of oppositely mounted quad-channel DRAMs.

FIG. 6A illustrates a second example device orientation using partial per-channel connections for a pair of oppositely mounted quad-channel DRAMs.

FIG. 6B illustrates a second example active to inactive partial per-channel connection correspondence for a pair of oppositely mounted quad-channel DRAMs.

FIG. 7A illustrates an example floorplan for a quad-channel DRAM and example worst-case latency paths in quad-channel mode.

FIG. 7B illustrates an example floorplan for a quad-channel DRAM and example worst-case latency paths in clamshell (dual-channel) mode.

FIG. 8 illustrates an example block diagram for two channels of a quad-channel DRAM.

FIG. 9 is a timing diagram illustrating example row accesses for a quad-channel DRAM in clamshell (dual-channel) mode.

FIG. 10 is a timing diagram illustrating example write accesses for a quad-channel DRAM in clamshell (dual-channel) mode.

FIG. 11 is a timing diagram illustrating example read accesses for a quad-channel DRAM in clamshell (dual-channel) mode.

FIG. 12 is a block diagram of a processing system.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In an embodiment, a dynamic random access memory (DRAM) device may have four channels (i.e., a quad-channel device.) In a first mode (i.e., quad-channel mode), these channels may all be operated independently of each other and each access (i.e., read and write) different internal memory cores. In another mode, two of the four channels may be inactivated (i.e., dual-channel mode.) The remaining active channels respectively access the internal memory cores that otherwise would have been accessed by the inactivated channels. In an embodiment, the data width of the active channels is the same as the data width used in the quad-channel mode. The arrangement of the DRAM package balls is such that when two DRAM devices being operated in dual-channel mode, and are aligned on opposite sides of a substrate, they appear, to a memory controller, electrically and logically as a single quad-channel device being operated in four-channel mode. This type of arrangement allows each of the command/address (C/A) and data (DQ) buses, to be routed point-to-point. Since all of the signal routing is point-to-point, branches to reach multiple devices on the same signal line are not required.

Mounting two DRAM devices that are aligned on opposite sides of a substrate, and operating them as a single channel having twice the memory capacity can be referred to as clamshell mode. At high data rates, this type of arrangement requires short signal branches (a.k.a., stubs) off of the main signal traces of the command/address (C/A) bus in order to reach the two devices (rather than no stubs required to reach only one device.) Because these branches are relatively short (e.g., the thickness of the substrate) it is an efficient way of doubling the capacity of a memory channel without excessively loading the C/A signals while also keeping the data bus signals (DQs) point-to-point.

FIG. 1A is a block diagram illustrating a first mode of a quad-channel DRAM. In FIG. 1A, DRAM device 101 is configured with four active channels: channel A 110 a, channel B 110 b, channel C 110 c, and channel d 110 d. The active circuitry/logic for channel A 110 a when DRAM device 101 is configured in the four active channel (a.k.a., quad-channel) mode comprises a set of memory cores 114 a that are accessed via channel A, channel A control circuitry 113 a, channel A interface (I/F) circuitry 112 a, and channel A electrical connection points 111 a. The active circuitry/logic for channel B 110 b when DRAM device 101 is configured in quad-channel mode comprises a set of memory cores 114 b that are accessed via channel B, channel B control circuitry 113 b, channel B interface (I/F) circuitry 112 b, and channel B electrical connection points 111 b. The active circuitry/logic for channel C 110 c when DRAM device 101 is configured in quad-channel mode comprises a set of memory cores 114 c that are accessed via channel C, channel C control circuitry 113 c, channel C interface (I/F) circuitry 112 c, and channel C electrical connection points 111 c. The active circuitry/logic for channel D 110 d when DRAM device 101 is configured in quad-channel mode comprises a set of memory cores 114 d that are accessed via channel D, channel D control circuitry 113 d, channel D interface (I/F) circuitry 112 d, and channel D electrical connection points 111 d.

Channel A electrical connection points 111 a are operatively coupled to interface circuitry 112 a. Interface circuitry 112 a is operatively coupled to control circuitry 113 a and memory cores 114 a. Control circuitry 113 a is operatively coupled to interface 112 a. Control circuitry 113 a receives commands and addressed from interface circuitry 112 a. These commands include commands to access (i.e., read, write, activate, precharge, etc.) one or more of memory cores 114 a. In the case of a write command, data received at interface 112 a via electrical connection points 111 a is coupled to one or more of memory cores 114 a to be stored. In the case of a read command, the addressed one or more of memory cores 114 a couples retrieved data to interface 112 a to be transmitted via electrical connection points 111 a.

Channel B electrical connection points 111 b are operatively coupled to interface circuitry 112 b. Interface circuitry 112 b is operatively coupled to control circuitry 113 b and memory cores 114 b. Control circuitry 113 b is operatively coupled to interface 112 b. Control circuitry 113 b receives commands and addressed from interface circuitry 112 b. These commands include commands to access one or more of memory cores 114 b. In the case of a write command, data received at interface 112 b via electrical connection points 111 b is coupled to one or more of memory cores 114 b to be stored. In the case of a read command, the addressed one or more of memory cores 114 b couples retrieved data to interface 112 b to be transmitted via electrical connection points 111 b.

Channel C electrical connection points 111 c are operatively coupled to interface circuitry 112 c. Interface circuitry 112 c is operatively coupled to control circuitry 113 c and memory cores 114 c. Control circuitry 113 c is operatively coupled to interface 112 c. Control circuitry 113 c receives commands and addressed from interface circuitry 112 c. These commands include commands to access one or more of memory cores 114 c. In the case of a write command, data received at interface 112 c via electrical connection points 111 c is coupled to one or more of memory cores 114 c to be stored. In the case of a read command, the addressed one or more of memory cores 114 c couples retrieved data to interface 112 c to be transmitted via electrical connection points 111 c.

Channel D electrical connection points 111 d are operatively coupled to interface circuitry 112 d. Interface circuitry 112 d is operatively coupled to control circuitry 113 d and memory cores 114 d. Control circuitry 113 d is operatively coupled to interface 112 d. Control circuitry 113 d receives commands and addressed from interface circuitry 112 d. These commands include commands to access one or more of memory cores 114 d. In the case of a write command, data received at interface 112 d via electrical connection points 111 d is coupled to one or more of memory cores 114 d to be stored. In the case of a read command, the addressed one or more of memory cores 114 d couples retrieved data to interface 112 d to be transmitted via electrical connection points 111 d.

Channel A-D electrical connection points 111 a-111 d may correspond to pads, package pins, solder balls, or other means of electrically connecting a DRAM integrated circuit to a substrate, such as a printed circuit board. Memory cores 114 a-114 d may comprise dynamic random access memory (DRAM) array or other type of memory arrays, for example, static random access memory (SRAM) array, or non-volatile memory arrays such as flash.

It should be understood from the foregoing that, in quad-channel mode, each of channels A-D 110 a-110 d comprise enough active circuitry and electrical connection points 111 a-111 d to each operate independently of each other channel A-D 110 a-110 d. Each of channels A-D 110 a-110 d in quad-channel mode operate the command, address, and data transfer functions of their respective channel A-D 110 a-110 d independently of the other channels A-D 110 a-110 d.

In an embodiment, each of channels A-D 110 a-110 d includes nine (9) bidirectional data (DQ) lines (eight data lines and one for error-detection, correction, and/or parity.) In another embodiment, each of channels A-D 110 a-110 d includes eight (8) bidirectional data (DQ) lines. Each of channels A-D 110 a-110 d includes a C/A bus. Each of the channel A-D 110 a-110 d C/A busses include separate and independent, from the other C/A busses, data bus inversion (DBI), error detection (EDC), and timing signals (e.g., write strobes).

In an embodiment, each channel A-D 110 a-110 d may each receive one or more independent clocking signal(s) (not shown in FIGS. 1A-1B) that drive the operations of that respective channel A-D 110 a-110 d. In another embodiment, channels A-D 110 a-110 d may all share the one or more clock signal(s). Even though channels A-D 110 a-110 d function independently, their operations are driven by, and aligned to, the common clocking signal(s). In another embodiment, two channels A-D 110 a-110 d may share common clocking signal(s). For example, channel A 110 a and channel B 110 b may share a clocking signal while channel C 110 c and channel D 110 d share another clocking signal.

FIG. 1B is a block diagram illustrating a second mode of a quad-channel DRAM. In FIG. 1B, DRAM device 101 is configured with two active channels: channel A 110 a, and channel D 110 d. Thus, in this dual-channel mode, channel B electrical connection points 111 b, channel B interface circuitry 112 b, and channel B control circuitry 113 b are inactivated, unused, and/or powered off. Likewise, in this dual-channel mode, channel C electrical connection points 111 c, channel C interface circuitry 112 c, and channel B control circuitry 113 c are inactivated, unused, and/or powered off.

However, in the dual-channel modes, memory cores 114 b and memory cores 114 ca re configured to be accessed via the remaining two active channels. For example, memory cores 114 b may be accessed via channel A 110 a, and memory cores 114 c may be accessed via channel D 110 d. Memory cores 114 b being able to be accessed via channel A 110 a in the dual-channel mode is illustrated in FIG. 1B by the arrows from channel A interface 112 a and channel A control circuitry 113 a to and from memory cores 114 b (which in quad channel mode are accessed via channel B 110 b.) Memory cores 114 c being able to be accessed via channel D 110 d in the dual-channel mode is illustrated in FIG. 1B by the arrows from channel D interface 112 d and channel D control circuitry 113 d to and from memory cores 114 c (which in quad channel mode would be accessed via channel C 110 c.) Thus, in an embodiment, the amount of memory accessible via channel A 110 a is increased in the dual-channel mode (e.g., doubled if memory cores 114 a and 114 b each have the same capacity.) Likewise, the amount of memory accessible via channel D 110 d is increased in the dual-channel mode (e.g., doubled if memory cores 114 c and 114 d each have the same capacity.)

As described herein, in an embodiment, sets of two channels A-D 110 a-110 d may share common clocking signal(s). In an embodiment, the pairs of channels that share common clocking signals include one channel (e.g., channel A) that is active in the second mode and one channel that is inactive in the second mode (e.g., channel B).

FIG. 1C is a block diagram illustrating example active circuitry when the quad-channel DRAM is in the second mode. In FIG. 3 , the inactive, unused, and/or powered down circuitry is not shown. The circuitry that is active in the dual-channel mode is shown. Thus, in FIG. 1C, channel A electrical connection points 111 a, channel A interface circuitry 112 a, control circuitry 113 a, memory cores 114 a, memory cores 114 b are shown. FIG. 1C also illustrates the active couplings in dual-channel mode between: interface circuitry 112 a and control circuitry 113 a; control circuitry 113 a and memory cores 114 a; control circuitry 113 a and memory cores 114 b; memory cores 114 a and interface circuitry 112 a; and memory cores 114 b and interface circuitry 112 a. Likewise, in FIG. 1C, channel D electrical connection points 111 d, channel D interface circuitry 112 d, control circuitry 113 d, memory cores 114 d, memory cores 114 c are shown. FIG. 1C also illustrates the active couplings in dual-channel mode between: interface circuitry 112 d and control circuitry 113 d; control circuitry 113 d and memory cores 114 d; control circuitry 113 d and memory cores 114 c; memory cores 114 d and interface circuitry 112 d; and memory cores 114 c and interface circuitry 112 d.

FIG. 2A illustrates a first and second quad-channel DRAM oppositely mounted to utilize dual-channel mode. In FIGS. 2A-2B, memory system 200 comprises a first quad-channel device 201, a second quad-channel device 1201, and a substrate 250. The first quad-channel device 201 is disposed on a first side of substrate 250. The second quad-channel device 1201 is disposed on a second and opposite side of substrate 250. In FIG. 2 , the active electrical connection points 211 a and 211 d of the first quad-channel device 201 are illustrated. Active electrical connection points 211 a (e.g., channel A electrical connection points 111 a) are illustrated in the upper left quadrant of quad-channel device 201 (as viewed through the top of the package, where the electrical connection points are on the bottom of the package.) Active electrical connection points 211 d (e.g., channel D electrical connection points 111 d) are illustrated in the lower right quadrant of quad-channel device 201. The upper right and lower left quadrants of quad-channel device 201 are illustrated as blank in FIG. 2A to represent electrical connection points (e.g., electrical connection points 111 b and 111 c, respectively) that are inactive, unused, and/or unconnected to substrate 250.

FIG. 2B illustrates, with the substrate removed for clarity, the first and second quad-channel DRAMs oppositely mounted to utilize dual-channel mode. In FIG. 2B, as in FIG. 2A, active electrical connection points 211 a are illustrated in the upper left quadrant of quad-channel device 201 (as viewed through the top of the package, where the electrical connection points are on the bottom of the package.) Active electrical connection points 211 d are illustrated in the lower right quadrant of quad-channel device 201 when viewed from the same perspective. The upper right and lower left quadrants of quad-channel device 201 are illustrated as blank in FIG. 2B.

In addition, in FIG. 2B, active electrical connection points 1211 a are illustrated in the upper right quadrant of quad-channel device 1201 (when viewed from the bottom of the package, where the electrical connection points are on the bottom of the package.) When viewed from the perspective of the top of quad-channel device 1211 a, electrical connection points 1211 a would be in the upper left quadrant of quad-channel device 1201. Note that when viewed from the respective tops of their packages, active electrical connections points 211 a and 1211 a occupy the same quadrant (i.e., upper left.) Thus, when in dual-channel mode, electrical connection points 211 a and 1211 a correspond to the same channel (e.g., channel A 111 a in FIGS. 1A-1C.) Likewise, but not shown in FIG. 2B, electrical connection points in the lower right quadrant of quad-channel device 1201 (when viewed from top of 1201) correspond to the same channel as electrical connection points 211 d of quad-channel device 201 (e.g., channel D 111 d in FIG. 1A-1C.)

It should be noted that the inactive upper right quadrant of quad-channel device 201 is aligned with and positioned opposite of active electrical connection points 1211 a of quad-channel device 1201. Likewise, but not shown in FIG. 2B, the inactive lower left quadrant of quad-channel device 201 is aligned with and positioned opposite of active electrical connection points in the lower right quadrant (viewed from the top) of quad-channel device 1201.

FIG. 3A illustrates a first example device orientation and active channel connections for a pair of oppositely mounted quad-channel DRAMs. In FIGS. 3A-3C, memory system 300 comprises a first quad-channel device 301, a second quad-channel device 1301, and a substrate 350. Quad-channel device 301 is disposed on a first side of substrate 350 with its bottom (i.e., side with electrical connections/solder balls/pins) towards substrate 350 (and away from the viewer of FIGS. 3A-3C.) When viewed from the perspective of FIGS. 3A-3C: device orientation marker 360 and channel A electrical connections 311 a of quad-channel device 301 are in the upper left quadrant; channel B electrical connections 311 b are in the upper right quadrant; channel C connections 311 c are in the lower left quadrant; and channel D connections 311 d are in the lower right.

Quad channel device 1301 is disposed on the opposite side of substrate 350 with its bottom towards substrate 350 (thus, towards the viewer of FIGS. 3A-3C.) When viewed from the perspective of FIGS. 3A-3C, device orientation marker 1360 and channel A electrical connections 1311 a of quad-channel device 1301 are in the lower left quadrant; channel B electrical connections 1311 b are in the lower right quadrant; channel C connections 1311 c are in the upper left quadrant; and channel D connections 1311 d are in the upper right.

As can be observed from FIGS. 3A-3C, when devices 301 and 1301 are in dual-channel mode, active channel A connections 311 a of device 301 are disposed opposite of and aligned with the inactive channel C connections 1311 c of device 1301; inactive channel B connections 311 b of device 301 are disposed opposite of and aligned with active channel D connections 1311 d of device 1301; inactive channel C connections 311 c of device 301 are disposed opposite of and aligned with active channel A connections 1311 a of device 1301; and, active channel D connections 311 d of device 301 are disposed opposite of and aligned with the inactive channel B connections 1311 b of device 1301.

FIG. 3B illustrates a first example device orientation and active channel connection symmetry for a pair of oppositely mounted quad-channel DRAMs. In FIG. 3B, channel connections 311 a-311 d and 1311 a-1311 d, and device orientation markers 360 and 1360 are disposed in the same positions as illustrated in FIG. 3A. A channel connection orientation marker 361 a is shown in the upper left corner of channel A connections 311 a. Channel connection orientation marker 361 b is shown in the upper right corner of channel B connections 311 b. Channel connection orientation marker 361 c is shown in the lower left corner of channel C connections 311 c. Channel connection orientation marker 361 d is shown in the lower right corner of channel D connections 311 d.

In an embodiment, channel connections 311 a-311 d have the same signal to physical position (e.g., grid location) layout except are mirrored from each other along one or more reflective symmetry lines. This is illustrated by the locations of connection orientations markers 361 a-361 c (which, for example, could correspond to a particular physical connection location—e.g., pad, ball, pin, etc.) Thus, for example, channel B connections 311 b have the same layout as the channel A connections 311 a except that, as illustrated by the locations of orientation markers 361 a and 361 b, the channel B connections 311 b are mirrored from the channel A connection positions along a line that lies between them. When mirrored along a vertical line (in FIG. 3B) between channel A connections 311 a and channel B connections 311 b, orientation marker 361 b (and corresponding other connection points etc.) moves to the righthand side of channel B connections 311 b as compared to the left-hand side of channel A connections 311 a.

Channel C connections 311 c have the same layout as the channel A connections 311 a except that, as illustrated by the locations of orientation markers 361 a and 361 c, the channel C connections 311 c are mirrored from the channel A connection positions along a line that lies between them. When mirrored along a horizontal line (in FIG. 3B) between channel A connections 311 a and channel C connections 311 c, orientation marker 361 c (and corresponding other connection points etc.) moves to the bottom of channel C connections 311 ca s compared to the top of channel A connections 311 a.

Channel D connections 311 d have the same layout as the channel A connections 311 a except that, as illustrated by the locations of orientation markers 361 a and 361 d, the channel D connections 311 d are mirrored from the channel A connection positions along two lines: a first symmetry line that lies between channel A connections 311 a and channel B connections 311 b (and also lies between channel C connections 311 c and channel D connections 311 d), and a second symmetry line that lies between channel A connections 311 a and channel C connections 311 c (and also lies between channel B connections 311 b and channel D connections 311 d). When mirrored along these lines (one horizontal line and one vertical in FIG. 3B), orientation marker 361 d (and corresponding other connection points etc.) move to the bottom right hand corner of channel D connections 311 d as compared to the top left-hand corner of channel A connections 311 a.

Since quad-channel device 301 and quad-channel device 1301 have the same layout of channel connections 311 a-311 d, 1301 a-1301 d, the physical connection positions of 1301 a-1301 d have the same mirroring. This is illustrated by the locations of orientation markers 1361 a-1361 d in FIGS. 3B-3C.

It should be understood that, in an embodiment, there may be one or more individual signals (e.g., low-speed signals such as a reset signal and/or reference voltages) that don't physically mirror perfectly. For example, a given data signal (e.g., DQ0) may mirror with another data signal (e.g., DQ4) that performs the same function and/or has the same meaning. In another embodiment, a majority or substantially all of the individual signals of a channel are mirrored with another channel and those that are not perfectly mirrored are close to the mirrored location so that a small amount of routing is used on the substrate between the DRAMs to connect them.

In an embodiment, the DRAM includes one or more registers to store a register value that determines top-side/bottom side modes such that the package balls are coupled to the internal circuits in a manner that the signals are mirrored between the two modes. For example, this register value (i.e., mode) may be set by a memory controller via one or more of the channels. The memory controller includes an interface that issues a mode register set (MRS) command, along with the register value to the memory device. The DRAM receives the MRS command and stores the register value in the register to set the top-side/bottom side (or other variants) mode. In another example, the register value may also be set using serial presence detect circuitry where parameter information pertaining to the DRAM, stored in a memory device (such as a serial presence detect (SPD) device) or the DRAM itself is read by the memory controller or other interface. The memory controller then, based on the parameter information, sets the top-side/bottom side mode using one of the methods described herein. In another example, the register value (or the top-side/bottom side mode) may be set by a signal (i.e., voltage) asserted on a pin during power-up, reset, and/or normal operating state The memory controller may assert the voltage on the pin which is included on the DRAM. In another embodiment, two different package designs can be used for when the device is placed on top of the substrate or the bottom so that the signals are mirrored. These different package designs may also be configured set the signal (i.e., voltage) on a pin of the DRAM that determines the mode.

FIG. 3C illustrates a first example active to inactive channel connection correspondence for a pair of oppositely mounted quad-channel DRAMs. As is illustrated in FIG. 3C, the physical location of orientation marker 361 a corresponds to the physical location of orientation marker 1361 c (but on the other side of substrate 350). Thus, the physical location of a pad/ball/etc. connection corresponding to a given signal in channel A 311 a corresponds to and is opposite of the physical location of a pad/ball/etc. of the same signal in channel C 1311 c. This is illustrated in FIG. 3C by arrow 371 running between orientation marker 361 a to orientation marker 1361 c. The same relationship holds for the physical connection locations of the individual signals of channel D connections 311 d and channel B connections 1311 b (illustrated by arrow 372 running between orientation marker 361 d and orientation marker 1361 b); the physical connection locations of the individual signals of channel C connections 311 c and channel A connections 1311 a (illustrated by arrow 373 running between orientation marker 361 c and orientation marker 1361 a); and, the physical connection locations of the individual signals of channel B connections 311 b and channel D connections 1311 d (illustrated by arrow 374 running between orientation marker 361 b and orientation marker 1361 d).

FIG. 4A illustrates a second example device orientation and active channel connections for a pair of oppositely mounted quad-channel DRAMs. In FIGS. 4A-4C, memory system 400 comprises a first quad-channel device 401, a second quad-channel device 1401, and a substrate 450. Quad-channel device 401 is disposed on a first side of substrate 450 with its bottom (i.e., side with electrical connections/solder balls/pins) towards substrate 450 (and away from the viewer of FIGS. 4A-4C.) When viewed from the perspective of FIGS. 4A-4C: device orientation marker 460 and channel A electrical connections 411 a of quad-channel device 401 are in the upper left quadrant; channel B electrical connections 411 b are in the upper right quadrant; channel C connections 411 c are in the lower left quadrant; and channel D connections 411 d are in the lower right.

Quad channel device 1401 is disposed on the opposite side of substrate 450 with its bottom towards substrate 450 (towards the viewer of FIGS. 4A-4C.) When viewed from the perspective of FIGS. 4A-4C, device orientation marker 1460 and channel A electrical connections 1411 a of quad-channel device 1401 are in the upper right; channel B electrical connections 411 b are in the upper left; channel C connections 1 411 c are in the lower right quadrant; and channel D connections 1411 d are in the lower left quadrant.

As can be observed from FIGS. 4A-4C, when devices 401 and 1401 are in dual-channel mode, active channel A connections 411 a of device 401 are disposed opposite of and aligned with the inactive channel B connections 1411 b of device 1401; inactive channel B connections 411 b are disposed opposite of and aligned with active channel A connections 1411 a of device 1401; inactive channel C connections 411 c are disposed opposite of and aligned with active channel D connections 1411 d of device 1401; and, active channel D connections 411 d of device 401 are disposed opposite of and aligned with the inactive channel C connections 1411 c of device 1401.

In an embodiment, channel connections 411 a-411 d and 1411 a-1411 d have the same signal to physical position (e.g., grid location) layout except are mirrored from each other along one or more reflective symmetry lines. This is illustrated by the locations of connection orientations markers 461 a-461 d and 1461 a-1461 d (which, for example, could correspond to a particular signal physical connection location.) The mirroring of physical connections to signal assignments along symmetry lines between channel connections 411 a-411 d and 1411 a-1411 d was discussed previously with reference to FIGS. 3A-3C (311 a-311 d and 1311 a-1311 d) and thus, for the sake of brevity, will not be repeated here.

FIG. 4C illustrates a second example active to inactive channel connection correspondence for a pair of oppositely mounted quad-channel DRAMs. As is illustrated in FIG. 4C, the physical location of orientation marker 461 a corresponds to the physical location of orientation marker 1461 b (but on the other side of substrate 450). Thus, the physical location of a pad/ball/etc. connection corresponding to a given signal in channel A 411 a corresponds to and is opposite of the physical location of a pad/ball/etc. of the same signal in channel B 1411 b. This is illustrated in FIG. 4C by arrow 471 running between orientation marker 461 a to orientation marker 1461 b. The same relationship holds for the physical connection locations of the individual signals of channel D connections 411 d and channel C connections 1411 c (illustrated by arrow 472 running between orientation marker 461 d and orientation marker 1461 c); the physical connection locations of the individual signals of channel C connections 411 c and channel D connections 1411 d (illustrated by arrow 473 running between orientation marker 461 c and orientation marker 1461 d); and, the physical connection locations of the individual signals of channel B connections 411 b and channel A connections 1411 a (illustrated by arrow 474 running between orientation marker 461 b and orientation marker 1461 a).

FIG. 5A illustrates a first example device orientation using partial per-channel connections for a pair of oppositely mounted quad-channel DRAMs. In FIGS. 5A-5B, memory system 500 comprises a first quad-channel device 501, a second quad-channel device 1501, and a substrate 550. Quad-channel device 501 is disposed on a first side of substrate 550 with its bottom (i.e., side with electrical connections/solder balls/pins) towards substrate 550 (and away from the viewer of FIGS. 5A-5B.) When viewed from the perspective of FIGS. 5A-5B: device orientation marker 560 and channel A electrical connections 511 aa-511 ab, of quad-channel device 501 are in the upper left quadrant; channel B electrical connections 511 ba-511 bb are in the upper right quadrant; channel C connections 511 ca-511 cb are in the lower left quadrant; and channel D connections 511 da-511 db are in the lower right.

Quad channel device 1501 is disposed on the opposite side of substrate 550 with its bottom towards substrate 550 (i.e., towards the viewer of FIGS. 5A-5B.) When viewed from the perspective of FIGS. 5A-5B, device orientation marker 1560 and channel A electrical connections 1511 aa-1511 ab of quad-channel device 1501 are in the lower left quadrant; channel B electrical connections 1511 ba-1511 bb are in the lower right quadrant; channel C connections 1511 ca-1511 cb are in the upper left quadrant; and channel D connections 1511 da-1511 db are in the upper right.

In FIGS. 5A-5B, channel connections 511 aa, 511 ba, 511 ca, 511 da, 1511 aa, 1511 ba, 1511 ca, and 1511 da are active in the dual-channel mode. Channel connections 511 ab, 511 bb, 511 cb, 511 d b, 1511 ab, 1511 bb, 1511 cb, and 1511 db are inactive in the dual-channel mode. Thus, for any given group of channel A, B, C, or D connections, a portion of the connections are active and a portion of the connections are inactive.

As can be observed from FIGS. 5A-5B, when devices 501 and 1501 are in dual-channel mode, the active portion of channel A connections 511 aa of device 501 are disposed opposite of and aligned with the inactive portion of channel C connections 1511 cb of device 1301; the inactive portion of channel B connections 511 bb are disposed opposite of and aligned with the active portion of channel D connections 1511 da of device 1501; the inactive portion of channel C connections 511 cb are disposed opposite of and aligned with the active portion of channel A connections 1511 aa of device 1501; the active portion of channel D connections 511 da of device 501 are disposed opposite of and aligned with the inactive portion of channel B connections 1511 bb of device 1501; the inactive portion of channel A connections 511 ab are disposed opposite of and aligned with the active portion of channel C connections 1511 ca; the active portion of channel B connections 511 ba are disposed opposite of and aligned with the inactive portion of channel D connections 1511 db of device 1501; the active portion of channel C connections 511 ca are disposed opposite of and aligned with the inactive portion of channel A connections 1511 ab of device 1501; and, the inactive portion of channel D connections 511 db of device 501 are disposed opposite of and aligned with the active portion of channel B connections 1511 ba of device 1501.

FIG. 5B illustrates a first example active to inactive partial per-channel connection correspondence for a pair of oppositely mounted quad-channel DRAMs. In particular, the physical location correspondence between signals in the inactive portion of channel C connections 511 cb and the physical location of signals in the active portion of channel A connections 1511 aa is illustrated by arrow 571. The physical location correspondence between signals in the active portion of channel B connections 511 ba and the physical location of signals in the inactive portion of channel D connections 1511 db is illustrated by arrow 572. Further discussion of the other physical location correspondences present between the active/inactive signals of devices 501 and 1501 are omitted herein for the sake of brevity.

FIG. 6A illustrates a second example device orientation using partial per-channel connections for a pair of oppositely mounted quad-channel DRAMs. In FIGS. 6A-6B, memory system 600 comprises a first quad-channel device 601, a second quad-channel device 1601, and a substrate 650. Quad-channel device 601 is disposed on a first side of substrate 650 with its bottom (i.e., side with electrical connections/solder balls/pins) towards substrate 650 (and away from the viewer of FIGS. 6A-6B.) When viewed from the perspective of FIGS. 6A-6B: device orientation marker 660 and channel A electrical connections 611 aa-611 ab, of quad-channel device 601 are in the upper left quadrant; channel B electrical connections 611 ba-611 bb are in the upper right quadrant; channel C connections 611 ca-611 cb are in the lower left quadrant; and channel D connections 611 da-611 db are in the lower right.

Quad channel device 1601 is disposed on the opposite side of substrate 650 with its bottom towards substrate 650 (i.e., towards the viewer of FIGS. 6A-6B.) When viewed from the perspective of FIGS. 6A-6B, device orientation marker 1660 and channel A electrical connections 1611 aa-1611 ab of quad-channel device 1601 are in the upper right quadrant; channel B electrical connections 1611 ba-1611 bb are in the upper left quadrant; channel C connections 1611 ca-1611 cb are in the lower right quadrant; and channel D connections 1611 da-1611 db are in the lower left.

In FIGS. 6A-6B, channel connections 611 aa, 611 ba, 611 ca, 611 da, 1611 aa, 1611 ba, 1611 ca, and 1611 da are active in the dual-channel mode. Channel connections 611 ab, 611 bb, 611 cb, 611 db, 1611ab, 1611 bb, 1611 cb, and 1611 db are inactive in the dual-channel mode. Thus, for any given group of channel A, B, C, or D connections, a portion of the connections are active and a portion of the connections are inactive.

As can be observed from FIGS. 6A-6B, when devices 601 and 1601 are in dual-channel mode, the active portion of channel A connections 611 aa of device 601 are disposed opposite of and aligned with the inactive portion of channel B connections 1611 bb of device 1601; the inactive portion of channel B connections 611 bb are disposed opposite of and aligned with the active portion of channel A connections 1611 aa of device 1601; the inactive portion of channel C connections 611 cb are disposed opposite of and aligned with the active portion of channel D connections 1611 da of device 1601; the active portion of channel D connections 611 da of device 601 are disposed opposite of and aligned with the inactive portion of channel C connections 1611 cb of device 1601, the inactive portion of channel A connections 611 ab of device 601 are disposed opposite of and aligned with the active portion of channel B connections 1611 ba of device 1601; the active portion of channel B connections 611 ba are disposed opposite of and aligned with the inactive portion of channel A connections 1611 ab of device 1601; the active portion of channel C connections 611 ca are disposed opposite of and aligned with the inactive portion of channel D connections 1611 db of device 1601; and, the inactive portion of channel D connections 611 db of device 601 are disposed opposite of and aligned with the active portion of channel C connections 1611 ca of device 1601.

FIG. 6B illustrates a first example active to inactive partial per-channel connection correspondence for a pair of oppositely mounted quad-channel DRAMs. In particular, the physical location correspondence between signals in the active portion of channel C connections 611 ca and the physical location of signals in the inactive portion of channel D connections 1611 db is illustrated by arrow 671. The physical location correspondence between signals in the inactive portion of channel B connections 611 bb and the physical location of signals in the active portion of channel A connections 1611 aa is illustrated by arrow 672. Further discussion of the other physical location correspondences present between the active/inactive signals of devices 601 and 1601 are omitted herein for the sake of brevity.

FIG. 7A illustrates an example floorplan for a quad-channel DRAM and example worst-case latency paths in quad-channel mode. In FIG. 7A, memory device 700 is configured with four active channels: channel A 710 a, channel B 710 b, channel C 710 c, and channel D 710 d. The active circuitry/logic for channel A 710 a when DRAM device 700 is configured in the four active channel (a.k.a., quad-channel) mode comprises a set of memory cores 714 a that are accessed using channel A data (DQ) circuitry 717 a, and channel A command/address (CA) circuitry 716 a. The active circuitry/logic for channel B 710 b when DRAM device 700 is configured in quad-channel mode comprises a set of memory cores 714 b that are accessed using channel B data (DQ) circuitry 717 b, and channel B command/address (CA) circuitry 716 b. The active circuitry/logic for channel C 710 c when DRAM device 700 is configured in quad-channel mode comprises a set of memory cores 714 c that are accessed using channel C data (DQ) circuitry 717 c, and channel C command/address (CA) circuitry 716 c. The active circuitry/logic for channel D 710 d when DRAM device 700 is configured in quad-channel mode comprises a set of memory cores 714 d that are accessed using channel D data (DQ) circuitry 717 d, and channel D command/address (CA) circuitry 716 d.

Also illustrated in FIG. 7A are example worst case access paths for each of the channels 710 a-710 d. An example worst case access path for CA distribution by channel A 710 a is illustrated by arrow 718 a. Arrow 718 a runs from channel A CA interface circuitry 716 a to the memory core 714 a in the upper-left corner of channel A circuitry 710 a. An example worst case data path returning from the memory core 714 a in the upper-left corner of channel A circuitry 710 a to channel A DQ interface circuitry 717 a is illustrated by arrow 719 a. Similar example worst case CA distribution access paths and DQ return paths are illustrated for channels B-D by arrows 718 b-718 d, and 719 b-719 d, respectively.

FIG. 7B illustrates an example floorplan for a quad-channel DRAM and example worst-case latency paths in clamshell (dual-channel) mode. In FIG. 7B, memory device 700 is configured with two active channels: channel A 710 a and channel D 710 d. The memory cores 714 b and 714 c accessed by channel B 710 b and channel C 710 c, respectively, in the quad channel mode are accessed by the circuitry (and interfaces) of channel A 710 a and channel D 710 d, respectively, when memory device 700 is in dual channel mode.

Also illustrated in FIG. 7B are example worst case access paths for each of the channels 710 a and 710 d. An example worst case access path for CA distribution for memory cores 714 a is illustrated by arrow 718 a. Arrow 718 a runs from channel A CA interface circuitry 716 a to the memory core 714 a in the upper-left corner of channel A circuitry 710 a. An example worst case data path returning from the memory core 714 a in the upper-left corner of channel A circuitry 710 a to channel A DQ interface circuitry 717 a is illustrated by arrow 719 a.

In dual-channel mode, the memory cores 714 b associated with channel B 710 b in the quad channel mode are now accessed via the channel A 710 a circuitry. An example worst case access path for CA distribution to memory cores 714 b is illustrated by arrow 720 b. Arrow 720 b runs from channel A CA interface circuitry 716 a to the memory core 714 b in the upper-right corner of channel B circuitry 710 b. An example worst case data path returning from memory core 714 b in the upper-right corner of channel B circuitry 710 b to channel A DQ interface circuitry 717 a is illustrated by arrow 721 b. Example worst case CA distribution access path and DQ return path are illustrated for channel C 710 c memory cores 714 cb y arrows 720 c and 721 c, respectively. Example worst case CA distribution access path and DQ return path are illustrated for channel D 710 d memory cores 714 d by arrows 718 d and 719 d, respectively.

In an embodiment, the extra length of access paths 720 b and 721 b, as compared to access paths 719 a and 719 b, may result in additional access latency. For example, 2 additional clock cycle/phases may be used—1 to account for increased CA distribution path delay (path 720 b) and 1 for increased DQ return path delay (path 721 b). In an embodiment, memory device 700 may be configured to also increase access latencies for channel A 710 a memory cores 714 a such that the all accesses via channel A 710 a, whether to memory cores 714 a or 714 b have the same access latency. In another embodiment, the access latencies to memory cores 714 a may be shorter than the access latencies to memory cores 714 b. In an embodiment, the most-significant bit (MSB) of the row address may determine whether the access latency is the shorter (i.e., to memory cores 714 a) or the longer (i.e., to memory cores 714 b) access latency. To allow for additional processing time in order to determine whether an access is to memory cores 714 a versus 714 b, memory device 700 may be configured to receive the MSB of the row access and the bank address early (or at the start of) the command sequence (e.g., received in the first and/or second cycles of the command/address information packet.) Receiving the MSB of the row access and the bank address (or whatever signals determine the quadrant of the access) early in the command sequence allows the decoding of the quadrant before the entire command/address is decoded. This reduces the path delay impact that would otherwise occur if the quadrant information was received later in the command sequence. In another embodiment, a bit of the column address may determine whether the access time is the shorter (i.e., to memory cores 714 a) or the longer (i.e., to memory cores 714 b) access time.

FIG. 8 illustrates an example block diagram for two channels of a quad-channel DRAM. In FIG. 8 , memory device 800 comprises channel A DQ interface circuitry 817 a, channel B DQ interface circuitry 817 b, channel A CA interface circuitry 816 a, channel B CA interface circuitry 816 b, channel A DQ logic 827 a, channel B DQ logic 827 b, channel A CA latch 826 a, channel B CA latch 826 b, clamshell mode decoder 840, internal clock (iCK) generation circuitry 845, channel A command logic 823 a, channel B command logic 823 b, channel A bi-directional tri-state buffers 837 a, channel B bi-directional tri-state buffers 837 b, internal CA steering tri-state buffers 841, internal DQ bus isolation/steering tri-state buffers 842, channel A associated memory banks 874 a-875 a, and channel B associated memory banks 874 b-875 b.

In an embodiment, DQ interface circuitry 817 a-817 b includes circuitry for nine (or alternately eight) bidirectional data signals (e.g., DQ[0:8] or DQ[0:7]), receiving a write clock signal (WCK), and a bidirectional data bus inversion (DBI) signal. Command address interface circuitry 816 a-816 b include circuitry for seven command/address signals (e.g., CA[0:6].) Internal clock generation circuitry 845 receives an external clock signal CK. Clock generation circuitry 845 generates and distributes internal clock signals iCK, iCK/2. iCK2 is a ½ frequency version of iCK and includes two phases separated by 180° (e.g., inversions of each other.)

Channel A associated memory banks 874 a-875 a are operatively coupled to internal command bus C (busC) 884 a and internal data bus E (busE) 887 a. Internal busC 884 a may include signals corresponding to a row address strobe (RAS), read column address strove (RCAS), write column address strobe (WCAS), and address signals (ADDR). Internal command busA′824 a is generated by command logic 823 a from signals received via the output of latch 826 a (i.e., busA 825 a). Internal busA 825 a (or a subset thereof—e.g., MSB of row address) is also provided to clamshell decoder logic 840. Internal busA′824 a may include signals corresponding to, for channel A associated memory banks 874 a-875 a and/or for channel B associated memory banks 874 b-875 b, RAS, RCAS, WCAS, and address signals (ADDR).

Channel B associated memory banks 874 b-875 b are operatively coupled to internal command bus B (busB) 884 b and internal data bus D (busD) 887 b. Internal busB 884 b may include signals corresponding to, for channel B associated memory banks 874 b-875 b, RAS, RCAS, WCAS, and address signals (ADDR).

Tri-state buffers 837 a selectively couple and uncouple DQ logic 827 a with internal data bus E (busE) 887 a under the control of write ready (WRrdy) and read ready (RDrdy) signals. Internal busE 887 a may include 256 data lines and the RDrdy signal. The RDrdy signal may be generated along with the data being read from a memory bank 874 a-875 a (and banks 874 b-875 b when memory device 800 is in clamshell mode) and acts as a handshake signal.

When not in clamshell mode, tri-state buffers 837 b selectively couple and uncouple DQ logic 827 b with internal data bus D (busD) under the control of B-channel write ready (BWRrdy) and B-channel read ready (BRDrdy) signals. Internal busD may include 256 data lines and the RDrdy signal. The RDrdy signal may be generated along with the data being read from a memory bank 874 b-875 b and acts as a handshake signal. Tri-state buffers 837 b do not couple DQ logic 827 b with busD 887 b when memory device 800 is in clamshell mode. Thus, in an embodiment, the signal BWRdy may be generated, at least in part, according to the following logical equation: BWRrdy=!CSm AND WRrdy, where CSm is a logical ‘1’ when memory device 800 is in clamshell mode, and the exclamation point represents a logical NOT (i.e., inversion) operation. The signal BRDrdy may be generated, at least in part, according to the following logical equation: BRDrdy=!CSm AND RDrdy.

Tri-state buffers 841 selectively drive internal command bus A′ (busA′) to either busB 884 b or busC 884 a. When memory device 800 is not in clamshell mode, clamshell decode 840 sets mdR15 signal 847 such that busA′ is driven to busC 884 a. When memory device 800 is in clamshell mode, clamshell decode 840 sets mdR15 signal 847 such that busA′ is driven to busC 884 a if the MSB of the row address (e.g., R15) is logical zero (0) and to busB 884 b if it is a logical one (1). Thus, in an embodiment, the signal mdR15 may be generated, at least in part, according to the following logical equation: mdR15=CSm AND R15.

Tri-state buffers 842 selectively couple busD 887 b to busE 887 a and vice versa under the control of the signals CWRrdy and CRDrdy. In non-clamshell mode, busD 887 b to busE 887 a are not coupled to each other. In clamshell mode, busD 887 b may be coupled to busE 887 a depending upon the value of the MSB of the row address (e.g., R15). The direction that signals are propagated between busD 887 b and busE 887 a depends upon whether the operation is a read or a write. Thus, in an embodiment, the signal CWRrdy may be generated, at least in part, according to the following logical equation: CWRrdy=CSm AND R15 AND WRrdy. The signal CRDrdy may be generated, at least in part, according to the following logical equation: CRDrdy=CSm AND R15 AND RDrdy.

Tri-state buffers 843 selectively couple outputs 824 b of command logic 823 b to busB 884 b. When in clamshell mode, the CSm signal tri-states the outputs of buffers 843 so that tri-state buffers 841 may drive busB 884 b. In an embodiment, the CSm mode signal can also disable channel B DQ interface circuitry 817 b, channel B CA interface circuitry 816 b, channel B DQ logic 827 b, and channel A command logic 823 a.

FIG. 9 is a timing diagram illustrating example row accesses for a quad-channel DRAM in clamshell (dual-channel) mode. The timings, signals, and functions illustrated in FIG. 9 may be used by one or more of memory device 101, memory system 200, memory system 300, memory system 400, memory system 500, memory system 600, memory device 700, memory device 800, and/or their components.

In FIG. 9 , an edge of internal clock, iCK, latches a first activate command (ACT1) on the CA interface and drives (at least) the activate command (ACT1), a first bank address (BA1), and the most significant bit of the row address (R15) onto busA (e.g., busA 825 a). This is illustrated in FIG. 9 by arrow 901. The value of R15 and the mode (i.e., clamshell mode) are logically combined to set mdR15 to a logical ‘1’ (e.g., mdR15=CSm AND R15=1.) This is illustrated in FIG. 9 by arrow 902. In other embodiments, different bits may be used to distinguish which memory bank(s) an access is directed to. For example, the most significant bit of the column address, or a bit in the command itself (rather than an address bit) may be used.

An edge of a half-frequency internal clock (e.g., iCK/2-180) times the driving of the activate command, the bank address, and the row address bits (except for the MSB R-15) onto busA′ and from busA′ to busB. This is illustrated by arrows 903 and 905, respectively. An edge of the half-frequency internal clock also times the assertion of a ‘command ready’ signal to the memory bank addressed by the bank address (e.g., memory banks 874 b-875 b.) This is illustrated by arrow 904.

Another edge of internal clock, iCK, latches a second activate command (ACT2) on the CA interface and drives (at least) the second activate command (ACT2), a second bank address (BA1), and the most significant bit of the row address onto busA (e.g., busA 825 a). The most significant bit of the row address is the opposite value as for the first activate command. This is illustrated in FIG. 9 using the notation !R15. The value of !R15 and the mode (i.e., clamshell mode) are logically combined to set mdR15 to a logical ‘0’ (e.g., mdR15=CSm AND !R15=0.) This is illustrated in FIG. 9 by arrow 906.

An edge of a half-frequency internal clock (e.g., iCK/2-180) times the driving of the second activate command, the second bank address, and the second row address bits (except for the MSB !R15) onto busA′ and from busA′ to busC. This is illustrated by arrow 907. An edge of the half-frequency internal clock also times the assertion of a ‘command ready’ signal to the memory bank addressed by the bank address (e.g., memory banks 874 a-875 a.)

FIG. 10 is a timing diagram illustrating example write accesses for a quad-channel DRAM in clamshell (dual-channel) mode. The timings, signals, and functions illustrated in FIG. 10 may be used by one or more of memory device 101, memory system 200, memory system 300, memory system 400, memory system 500, memory system 600, memory device 700, memory device 800, and/or their components.

An edge on the external clock CK initiates the processing of a first write command (WR1). A number of clock CK cycles later, first set of data bits (DATA1) on the external DQ signals is latched into the device by a write clock (WCK) over a number of cycles of WCK. This is illustrated by arrow 1001. This first set of data bits is addressed to a channel B memory bank 874 b-875 b (note value of mdR15). Thus, the first set of data bits (DATA1) is accompanied by Wrdy and steered to busD. This is illustrated by arrows 1002 and 1004.

Another edge on the external clock CK initiates the processing of a second write command (WR2). A number of clock CK cycles later, second set of data bits (DATA2) on the external DQ signals is latched into the device by a write clock (WCK) over a number of cycles of WCK. This second set of data bits is addressed to a channel A memory bank 874 a-875 a (note value of mdR15). Thus, the second set of data bits (DATA2) is accompanied by Wrdy and is steered to busE. This is illustrated by arrows 1003 and 1005.

FIG. 11 is a timing diagram illustrating example read accesses for a quad-channel DRAM in clamshell (dual-channel) mode. The timings, signals, and functions illustrated in FIG. 11 may be used by one or more of memory device 101, memory system 200, memory system 300, memory system 400, memory system 500, memory system 600, memory device 700, memory device 800, and/or their components.

An edge on the external clock CK initiates the processing of a first read command (RD1). A number of clock CK cycles later, first set of data bits (DATA1) are output on the external DQ signals. This is illustrated by arrow 1101. This first set of data bits comes from a channel B memory bank 874 b-875 b (note value of mdR15). Thus, the first set of data bits (DATA1) comes from busD and is latched using the Drdy signal. This is illustrated by arrow 1102.

Another edge on the external clock CK initiates the processing of a second read command (RD2). A number of clock CK cycles later, second set of data bits (DATA2) are output on the external DQ signals. This is illustrated by arrow 1103. This second set of data bits comes from a channel A memory bank 874 a-875 a (note value of mdR15). Thus, the second set of data bits (DATA2) is comes from busE and is latched using the Drdy signal. This is illustrated by arrow 1104.

The methods, systems and devices described above may be implemented in computer systems, or stored by computer systems. The methods described above may also be stored on a non-transitory computer readable medium. Devices, circuits, and systems described herein may be implemented using computer-aided design tools available in the art, and embodied by computer-readable files containing software descriptions of such circuits. This includes, but is not limited to one or more elements of memory device 101, memory system 200, memory system 300, memory system 400, memory system 500, memory system 600, memory device 700, memory device 800, and their components.

These software descriptions may be: behavioral, register transfer, logic component, transistor, and layout geometry-level descriptions. Moreover, the software descriptions may be stored on storage media or communicated by carrier waves.

Data formats in which such descriptions may be implemented include, but are not limited to: formats supporting behavioral languages like C, formats supporting register transfer level (RTL) languages like Verilog and VHDL, formats supporting geometry description languages (such as GDSII, GDSIII, GDSIV, CIF, and MEBES), and other suitable formats and languages. Moreover, data transfers of such files on machine-readable media may be done electronically over the diverse media on the Internet or, for example, via email. Note that physical files may be implemented on machine-readable media such as: 4 mm magnetic tape, 8 mm magnetic tape, 3-½ inch floppy media, CDs, DVDs, and so on.

FIG. 12 is a block diagram illustrating one embodiment of a processing system 1400 for including, processing, or generating, a representation of a circuit component 1420. Processing system 1400 includes one or more processors 1402, a memory 1404, and one or more communications devices 1406. Processors 1402, memory 1404, and communications devices 1406 communicate using any suitable type, number, and/or configuration of wired and/or wireless connections 1408.

Processors 1402 execute instructions of one or more processes 1412 stored in a memory 1404 to process and/or generate circuit component 1420 responsive to user inputs 1414 and parameters 1416. Processes 1412 may be any suitable electronic design automation (EDA) tool or portion thereof used to design, simulate, analyze, and/or verify electronic circuitry and/or generate photomasks for electronic circuitry. Representation 1420 includes data that describes all or portions of memory device 101, memory system 200, memory system 300, memory system 400, memory system 500, memory system 600, memory device 700, memory device 800, and their components as shown in the Figures.

Representation 1420 may include one or more of behavioral, register transfer, logic component, transistor, and layout geometry-level descriptions. Moreover, representation 1420 may be stored on storage media or communicated by carrier waves.

Data formats in which representation 1420 may be implemented include, but are not limited to: formats supporting behavioral languages like C, formats supporting register transfer level (RTL) languages like Verilog and VHDL, formats supporting geometry description languages (such as GDSII, GDSIII, GDSIV, CIF, and MEBES), and other suitable formats and languages. Moreover, data transfers of such files on machine-readable media may be done electronically over the diverse media on the Internet or, for example, via email

User inputs 1414 may comprise input parameters from a keyboard, mouse, voice recognition interface, microphone and speakers, graphical display, touch screen, or other type of user interface device. This user interface may be distributed among multiple interface devices. Parameters 1416 may include specifications and/or characteristics that are input to help define representation 1420. For example, parameters 1416 may include information that defines device types (e.g., NFET, PFET, etc.), topology (e.g., block diagrams, circuit descriptions, schematics, etc.), and/or device descriptions (e.g., device properties, device dimensions, power supply voltages, simulation temperatures, simulation models, etc.).

Memory 1404 includes any suitable type, number, and/or configuration of non-transitory computer-readable storage media that stores processes 1412, user inputs 1414, parameters 1416, and circuit component 1420.

Communications devices 1406 include any suitable type, number, and/or configuration of wired and/or wireless devices that transmit information from processing system 1400 to another processing or storage system (not shown) and/or receive information from another processing or storage system (not shown). For example, communications devices 1406 may transmit circuit component 1420 to another system. Communications devices 1406 may receive processes 1412, user inputs 1414, parameters 1416, and/or circuit component 1420 and cause processes 1412, user inputs 1414, parameters 1416, and/or circuit component 1420 to be stored in memory 1404.

The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art. 

What is claimed is:
 1. A dynamic random access memory (DRAM), comprising: at least four groups of memory cores; at least four memory access channel interfaces that, in a first mode, each respectively are to receive memory access commands, to receive memory access addresses, to receive data to be stored in a corresponding one of the groups of memory cores, and to transmit data retrieved from the corresponding one of the groups of memory cores; one-half of the at least four memory access channel interfaces to, in a second mode, each respectively receive memory access commands, receive memory access addresses, receive data to be stored in a corresponding two of the groups of memory cores, and transmit data retrieved from the corresponding two of the groups of memory cores; a first one-half of the at least four memory access channel interfaces to have first electrical connection conductors that lie on an opposing sides of a line of reflectional symmetry from second electrical connection conductors of a second one-half of the at least four memory access channel interfaces.
 2. The DRAM of claim 1, wherein the at least four memory access channel interfaces consists of four memory access channel interfaces, the first one-half of the at least four memory access channel interfaces consisting of a first memory access channel interface and a second memory access channel interface, the second one-half of the at least four memory access channel interfaces consisting of a third memory access channel interface and a fourth memory access channel interface.
 3. The DRAM of claim 2, wherein: the third memory channel access interface has third electrical connection conductors, and the fourth memory channel access interface has fourth electrical connection conductors; and, the first, second, third, and fourth electrical connection conductors each being disposed in separate physical quadrants.
 4. The DRAM of claim 3, wherein the first electrical connection conductors are disposed in a first physical quadrant, the second electrical connection conductors are disposed in a second physical quadrant, the third electrical connection conductors are disposed in a third physical quadrant, and the fourth electrical connection conductors are disposed in a fourth physical quadrant, the first and second physical quadrants being separated from the third and fourth physical quadrants along a first dividing line, the first and third physical quadrants being separated from the second and fourth along a second dividing line, the first and second dividing lines being substantially perpendicular to each other.
 5. The DRAM of claim 4, wherein each of the four memory access channel interfaces comprise a set of electrical connection conductors that are each configured to communicate a corresponding set of memory access channel signals, each of the set of memory access channel signals having a respective signal function, each of the set of memory access channel signals in each of the four memory access channel interfaces having a corresponding one of the set of memory access channel signals in each of the other of the four memory access channel interfaces with the same signal function.
 6. The DRAM of claim 5, wherein the corresponding signal functions associated with each of the first electrical connection conductors is disposed in reflective symmetry along the second dividing line to the corresponding signal functions associated with each of the second electrical connection conductors.
 7. The DRAM of claim 5, wherein the corresponding signal functions associated with each of the first electrical connection conductors is disposed in reflective symmetry along the first dividing line to the corresponding signal functions associated with each of the third electrical connection conductors.
 8. The DRAM of claim 5, wherein the corresponding signal functions associated with each of the first electrical connection conductors is disposed in reflective symmetry along the second dividing line to the corresponding signal functions associated with each of the second electrical connection conductors, the corresponding signal functions associated with each of the third electrical connection conductors is disposed in reflective symmetry along the second dividing line to the corresponding signal functions associated with each of the fourth electrical connection conductors, the corresponding signal functions associated with each of the first electrical connection conductors is disposed in reflective symmetry along the first dividing line to the corresponding signal functions associated with each of the third electrical connection conductors, and the corresponding signal functions associated with each of the second electrical connection conductors is disposed in reflective symmetry along the first dividing line to the corresponding signal functions associated with each of the fourth electrical connection conductors.
 9. A DRAM device, comprising: four groups of electrical connection points corresponding to, in a first mode, four memory channel interfaces, the four memory channel interfaces to, in the first mode, operate independently of each other to each access one of four respective sets of memory cores, where the four respective sets of memory cores are non-overlapping sets; a first two of the four groups of electrical connection points corresponding to, in a second mode, two memory channel interfaces, the two of the four memory channel interfaces to, in the second mode, operate independently of each other to each access one of two respective sets of memory cores, where the two respective sets of memory core are non-overlapping sets, a union of the two respective sets and a union of the four respective sets to result in an equivalent set of memory cores; and, the first two of the four groups of electrical connection points having, in the second mode, an arrangement of memory channel signal assignments that have reflective symmetry to each other.
 10. The DRAM of claim 9, wherein the four groups of electrical connection points as a whole are disposed within a first rectangle and each of the four groups of electrical connection points are each individually disposed within separate, non-overlapping, rectangles that are each within the first rectangle.
 11. The DRAM of claim 10, wherein each of the separate, non-overlapping rectangles are disposed within different quadrants of the first rectangle.
 12. The DRAM of claim 11, wherein the arrangement of memory channel signal assignments of the first two of the four groups of electrical connection points have, in the second mode, reflective symmetry to each other along a first axis line that divides a first two of the quadrants of the first rectangle from a second two of the quadrants of the first rectangle, the first two quadrants and the second two quadrants being non-overlapping.
 13. The DRAM of claim 12, wherein the arrangement of memory channel signal assignments of the first two of the four groups of electrical connection points have, in the second mode, reflective symmetry to each other along a second axis line that divides a third two of the quadrants of the first rectangle from a fourth two of the quadrants of the first rectangle, the third two quadrants and the forth two quadrants being non-overlapping, a first quadrant being a one of the first two quadrants and the third two quadrants, a second quadrant being a one of the second two quadrants and the fourth two quadrants.
 14. The DRAM of claim 9, wherein the arrangement of memory channel signal assignments of the first two of the four groups of electrical connection points is the same for the first mode and the second mode.
 15. The DRAM of claim 10, wherein, a second two of the four groups of electrical connection points correspond to memory channel interfaces that are activated in the first mode and deactivated in the second mode.
 16. A DRAM device, comprising: a package having a rectangular array of signal connection points, the signal connection points grouped into first, second, third, and fourth quadrants of the rectangular array, each of the first, second, third, and fourth quadrants serving as connection points for a first, a second, a third, and a fourth memory channel, respectively; at least one DRAM integrated circuit disposed attached to the package, the at least one DRAM integrated circuit to, in a first mode, operate each of the first, second, third, and fourth memory channels independent of each of the other of the first, second, third, and fourth memory channels, the at least one DRAM integrated circuit to, in a second mode, operate the first and third memory channels and disable the second and fourth memory channels.
 17. The DRAM device of claim 16, wherein the first quadrant is adjacent to the second quadrant and the fourth quadrant, and the third quadrant is adjacent to the second quadrant that the fourth quadrant.
 18. The DRAM device of claim 17, wherein, in the second mode, a first signal arrangement assigned to a majority of the signal connection points of the first memory channel has reflectional symmetry along a first dividing line to a second signal arrangement assigned to the signal connection points of the third memory channel, the first dividing line disposed between the first quadrant and the fourth quadrant and also disposed between the second quadrant and the third quadrant.
 19. The DRAM device of claim 17, wherein, in the second mode, a first signal arrangement assigned to a majority of the signal connection points of the first memory channel has reflectional symmetry along a first dividing line to a second signal arrangement assigned to the signal connection points of the third memory channel, the first dividing line disposed between the first quadrant and the second quadrant and also disposed between the third quadrant and the fourth quadrant.
 20. The DRAM device of claim 17, wherein, in the second mode, a first signal arrangement assigned to a majority of the signal connection points of the first memory channel has reflectional symmetry along a first dividing line and a second dividing line to a second signal arrangement assigned to the signal connection points of the third memory channel, the first dividing line and the second dividing line collectively defining the first, second, third, and fourth quadrants. 